Energy storage device



FIG. 1 is a perspective view of an energy storage device showing our new design, shown in an environment of use;

FIG. 2 is a perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a back view thereof;

FIG. 7 is a left view thereof; and,

FIG. 8 is a right view thereof.

The broken lines present in the figures are included for the purpose of showing environmental subject matter and form no part of the claimed design. 

CLAIM The ornamental design for an energy storage device, as shown and described. 